Automatic drilling mechanism



Oct. 6, 1953 H, R, ADCOCK AUTOMATIC DRILLING MECHANISM 4 Sheets-Sheet l Filed June l2,` 1950 Oct. 6, 1953 H. R. ADcocK AUTOMATIC DRILLING MECHANISM 4Sheets-Sheet 2 Filed June 12, 1950 Zinn ela-of Oct. 6, 1953 H. R. ADcocK AUTOMATIC DRILLING MECHANISM 4 Sheets-Sheet 3 H. R. A DcocK AUTQMATIC DRILLING MECHANISM Oct. 6, 1953 4 Sheets-Sheet 4 Filed June l2, 1950 Patented Oct. 6, 1953 UNITED STATES PATENToFFIcE AUTOMATIC DRILLING MECHANISM Horace Ray Adcock, Shirley, Birmingham, England, assigner to A. C. Wickman Limited, Tile Hill, Coventry, England Application June 12, 1950, 'serial No. 167,656 In Great Britain June 22, 194i).

intermittently withdrawing the drill when operating on a given work piece involves a loss of time, and in the mass production of some types of work pieces, this loss in the aggregate adds substantially to the cost of production.

The present invention is Yparticularly concerned with solving the problem of effecting such relief drilling Whilst applying a continuous working feed to the drilling unit. Such continuous feed motions are imparted to the tool slides of automatic lathes (multiand single spindle) and like machines, during their working stroke.

It is an object of .this invention to provide an automatic drilling unit for mounting upon such a tool slide whereby the working feed applied to 7 Claims. (Cl. 77-32-3) Figure 1 is a side'elevation of a mechanism embodying the invention;

Figure 2 is a part sectional inverted plan. Figure 3 is an endr View of the forward end of the mechanism, and

Figure 4 is across section on the line 4 4,

Y Figure 1.

the drill is derived from the feedslide movement and there are superimposed by the unit intermittent reciprocatory relieving movements ofthe drill. During such relieving movements the ,drill point is retracted by a distance from the open end of the hole suiiicient to clear a workpiece being drilled and returned to an operative position by advancing the drill by a distance equal to the distance through which it was retracted less the distance through which the unit has been fed bodily by the machine tool slide during the retraction and return of the drill. f

The invention comprises an automatic drilling unit for mounting upon atool slideof a machine towhich slide continuous uniform uninterrupted feed motion is imparted during the entire drilling operation,comprisingin combination asupport for a slidably mountedV drill holder, mech-` anism for effecting' intermittent reciprocating movements of the drill holder to retract the drill holder from and return it to an operative drilling position, tripping Ymeans for initiating successive reciprocatorypmovements, means op-` erable by said mechanism for varyingfthe opera` tive position of the drill Mholder to nullify the feedincrement imparted by theY tool slide during each vreciprocatiom there being provided upon the machine `frame a plurality of stationary means spaced in the direction of feed for intermittently co-operating with said trippingmeans.

In the accompanying drawings:U`

Figures 5-8 are diagrams illustrating successive stages in the action of the mechanism.

Figure 9 shows diagrammatically with respect to time, a complete cycle of the relative positions of a feed-slide and drill point, and the successive positions of the slide where the mechanism thereon is moved past and is tripped by the stationary tappet piece.

Referring to the drawings, there is provided a drill slide a which carries a hollow spindle b in the forward end of which is mounted a drill chuck c.l The rear end of the spindle is adapted to effect a slidable spline connection with a rotary drill-driving spindle d forming part. of an automatic (single or multi-spindle) lathe. The slide a in4 one convenient form is reciprocably mounted on a pair ofparallel guide bars e secured to a gear box f through which extends the drill-driving spindle d and which is adapted to be mounted on a feed slide g (Figures 3 and 4) of the lathe. Theslide g executes a continuous uniform feed movement (leftward in Figure 1).V

The spindle d drives a pinion h in the box, and this pinion engages another pinion i which actuates a worm 7' and worm wheel k.V The worm wheel lc drives a pinion m through a dog clutch member n loaded by a spring o, the member n being inv engagementY at one end with the wheel m and being engageable at the other end with the worm`Y wheel k'through .ratchet-like teeth p formed yon the parts k, n. The pinion m engages and imparts motion to the toothed periphery of a crank disc q.

The crank disc q imparts reciprocatory movements to the drill slide a throughpa connecting rod 1*, and to nullifythe eifect of the continuous movement of the feed slide g on the drill position while the drill is being retracted from and returned to the work piece, one end of the connecting rod is connected to one end of a bell crank lever s which is pivoted at its elbow on the drill slide a, the other end of this lever being loaded by a spring t through a plunger u carried by the said slide. On' the endof the lever to which the connecting rod is attached, there isarranged coaxially with the pivot v bywhich the connecting rod is attached tothe lever, a compensating cam w the periphery of which bears against an abutment .r vonv the drill slide. The

reciprocatory movements are therefore imparted to the drill slide from the connecting rod through the lever s, cam w and abutment Around each half of the periphery of the cam are formed a series of notches of progressively varying depth and the abutment a: is shaped to occupy each recess in turn, so that the distance between the drill slide and the crank aXis can be progressively reduced during the drilling operation. Coaxially with and secured to one side of the cam is a ratchet wheel 3 which is engaged by a pawl 4 loaded by a spring through a plunger 6 on the connecting rod. The arrangement is such that during each rotation of the crank the cam is moved through an angular distance corresponding to the pitch of the camrecesses. Movement of the cam from one position to the :next

into position for actuating this cam. At the end of the first half revolution of the crank the various parts occupy'the relative positions shown in Figure 7. During the second half of the rotation of the crank disc, the drill is returned to the Working position, the compensating cam is adenables the drill slide, under the actiongof. the

spring acting on the bell crank lever to recede by an amount equal to that by which thelfeed slide has advanced while the drill. i'sbeingwitlidrawn and returned. The unit is mountedupon the machine tool vslide in such aposition relative to the end of a workpiece, that in the drill,- ing position of the unit (that is with the parts as shown in Figure 1), the distance from the workpiece to the drill point is initially small, and upon retraction of the drill by rotation of the crank disc through 180" as later explained in detail, this distance will be a maximum. When the depth of a hole being drilled in the workpiece approaches the distance through which the drill is retracted by a 180 rotation of the crank disc from the position shown in Figure 1, the drill point will only slightly clear the end of the workpiece when the drill is fully retracted.

It will be understood that while the drill is cutting, the crank mechanism is Aout of action, and the drill is fed forward into'the work piece by the action of the feed slideg. But after the drill has penetrated the work piece to a predetermmed depth the crank mechanism is set in motion for withdrawing the drill and subsequently returning it to the work piece. To effect the automatic control of the clutch through which the crank mechanism is actuated, there is mounted in the gear box above mentioned a lever 'l which at one end is provided with a projection 8 adapted to enter a cam groove 8 formed around one half of the periphery of theslidable member n of the clutch, one side of this groove by its co-operation with the projection being adapted to eiect disengagement of the clutch. The intermediate part of the periphery of the said clutch member n is provided with a cam 10.(see Figures 5-8) adapted to rock the'leverv 1 about its pivot through a projection Il, for the purpose to be mentioned later. The other end of the lever carries a pawl i2 loaed'by a spring [3 adapted to co-operate with a series of appropriately spaced teeth I4 formed on a tappet piece l5 secured to the guide I6 which carries a feed slide g.

Referring now more particularly to Figures 5-8, the arrangement is such that during the initial part of the drilling operation, the clutch n is held out of action by the engagement of the projection 8 on the lever 'I with one side of the cam groove 9 in the slidable clutch member n. When the drill has penetrated the Work piece to a predetermined depth, the pawl l2 on the clutch lever l strikes one of the teeth I4 on the tap-pet piece l5 as shown in Figure 5. This causes the lever l to move and withdraw its projection 8 from therclutch member n. The latter then engages the complementary clutch member OIL the vanced by one notch, and the projection 8 on the clutch lever falls back into the groove 9 on the clutch member n as shown in Figure 8. At the end of one rotation of the crank disc, the clutch lever disengages the clutch, and the drilling then proceeds under the action of the feed slide until the paWl on the clutch lever lstrikes the 'next tooth on the tappet 'piece when the above described action is repeated. The number of repetitions of the said action and the intervals between them, depend on the length of the hole to be produced, and are determined by the number and spacing of the teeth on the tappet piece.

After the completion of the hole the feed slide is returned to its initial position in readiness for action on the next work piece, and as during the previous operation the compensating cam w was moved through only one half a revolution, it is necessary to impart an initial movement tc this cam for bringing the second series of notches around the other half of its periphery into operation. To effect this an additional tooth Il is provided on the tappet piece I5 and suitably spaced from the first of the other teeth, the lever 'I and pawl i2 being in such -a position as that shown in Figure 6 while the feed slide is being retracted to its initial position. y

In Figure 9, there is illustrated diagrammatically the successive positions of the feed-slide from the moment it is in slow feed to the workpiece surface A-A until the moment it has been rapidly retracted upon completion of drilling then halted in readiness for a similar cycle on another workpiece. The slow feed of the feedslide occupies the interval S1 to- S2 and the rapid retraction S2 to Ss. S3 corresponds to Si, that is, the beginning of a repeated similar cycle. Where the feed-slide is in advance of the drill point as a result of successive reliefs of the drill point, the movement of the slide is represented by broken lines. The intervals between the lines drawn parallel to the workpiece surface A-A represent the intervals between the teeth on the tappet piece l5. The points of intersection of these lines with line SiSz, indicate the moments when the crank mechanism is tripped and the drill point reciprocated to reset its forward position in relation to the feed-slide. The feed-slide movements are superimposed upon those of the drill point.

Considering the drill point at the beginning of a cycle to be at al (Figure 9), with the slide in slow feed and the cam w set so that the deepest notch of one set of the notches thereon receives the abutment zr, the crank mechanism starts to Withdraw the drill point to the position b1 at-the instant the mechanism on the feed-slide contacts the resetting tooth l1. During the withdrawal, the cam becomes reset so that the shallow'est notch of the other set of notches receives the abutment zc, thus taking up the lag of the drill `point behind the slide which accumulated inaJ previous drilling operation. .The crank mechanism returns the drill point from position b1 to present the point to the workpiece surface. Owing to continued feed-slide movement, the drill point is shown carried (downwardly and leftwards in Figure 9) to position ci. I

From c1 to di drilling occurs, and the feed-slide and drill point are fed in phase without lag. On arriving at d1 the mechanism on Vthe feedslide contacts tooth Ida. The crank thereupon reciprocates the drill so that the'drill point withdraws to b2 outside the workpiece and is then returned to ci in the workpiece at the same depth as di. This depth is the same owing to the further resetting of the cam which occurred during this last reciprocation to bring the notch next in greater depth to effectively subtract from the forward movement derived from the crank the distance by which the feed-slide has advanced during this reciprocation.

The drill point at ci owing to the reciprocation dibzcz now lags behind the slide by an amount equal to the horizontal distance in the figure from c2 to the broken line 1182.

Drilling again proceeds with the feed-slide ahead of, but in xed relation to, the drill point as the latter increases depth in the workpiece as indicated by the drilling interval cada.

Further reciprocations of the drill point with consequential resetting of the cam w to compensate for the interim advance of the continuously advancing feed-slide, take place as indicated by dzbscs, 01311404, 11417505 and finally ii-,hada when the mechanism on the slide contacts the respective teeth Mb, |40, ldd, and Me.

It will be seen that the total drilling period is the sum of the intervals from the start to the end, namely of crdi, czda, c3113J c4d-i and c5d5. The total lag of the drill point behind the feed-slide is represented by the horizontal distance of S2 from d5. The final reciprocation d5b5a2 of the drill point in the cycle begins when the point Sz is reached by the feed-slide. At that instant the slide is rapidly withdrawn to S3 during which the drill is again reciprocated, its final position being represented by a2. Having been withdrawn to S3 the feed slide occupies the starting position for similar cycle on another workpiece. The position of the drill point a2 corresponds to a1.

By this invention the intermittent withdrawal I of the drill for clearing the obstructive cuttings from the drill and applying cooling fluid to the end of the drill, can be effected not only conveniently but in` a manner which involves a minimum of loss of time.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

l. An automatic drilling unit for mounting upon a tool slide of a machine to which slide continuous uniform uninterrupted feed motion is imparted during the entire drilling operation, comprising in combination a drill holder, a slidably mounted support for said drill holder, mechanism for effecting intermittent reciprocating movements of the drill holder to retract the drill holder from and return it to an operative drilling position, a plurality of stationary means provided on the machine and spaced in the direction of feed, tripping means for initiating successive reciprocatory movements by intermittently co-operating with one of said stationary means, and means operable by said mechanism for varying the operative position of the'dill holder to nullify the feed increment im-` parted tion.v

2. An automatic drilling unit for mounting upon a'tool slide of a machine to which slide continuous uniform uninterrupted feed motion is imparted during the Aentire drilling operation, comprising in combination a drill holder, a slidably mounted support for the drill holder, a crank mechanism for eifecting intermittent re- 'ciprocatory movements of the drill holder to retract the drill holder from and return it to an operative drilling position, clutch means adapted to drive the crank mechanism, a plurality of stationary means provided upon the machine and spaced in the direction of feed, tripping means for controlling the clutch means by intermittently co-operating with one of said stationary means, and further means operable by said crank mechanism for varying the operative position of the drill holder to nullify the feed increment imparted by the tool slide during each reciprocation.

3. An automatic drilling unit for mounting upon a tool slide of a machine to which slide continuous uniform uninterrupted feed motion is imparted during the entire drilling operation comprising in combination a drill holder, a slidably mounted support for the drill holder, a crank mechanism for effecting intermittent reciprocating movements of the drill holder to retract the drill holder from and return it to an operative drilling position, clutch means adapted to drive the crank mechanism, a plurality of stationary means provided upon the machine and spaced in the direction of feed, tripping means bythe tool vslidev during each reciproca- -for controlling the clutch means by intermittently co-operating with one of said stationary means, and a compensatory cam and follower operatively arranged between the crank mechanism and the drill holder which cam is set by y clutch means, and a connecting rod pivoted at one end upon the crank disc and operatively connected at its other end to the drill holder by the compensatory cam and follower.

6. An automatic drilling unit as claimed in claim 5, and in combination with a lever pivoted on the drill holder, a ratchet wheel arranged coaxially with and secured' to the compensatory cam which is rotatably carried by the lever, an abutment mounted on the drill holder and constituting the follower, spring-means acting on the lever to urge the cam and follower into operative engagement, and a spring-loaded pawl carried by the connecting rod and co-operating with the ratchet wheel for imparting intermittent rotary motion to the cam under the action of the crank disc, each such intermittent motion causingv the cam to be reset in readiness for renewed drilling.

'7. An automatic drilling unit for mounting upon a tool slide of a machine to which slide continuous uniform uninterrupted feed motion is imp rising in combination a drill holder, a fslidably mounted -support for the Ydrill holder, a crank mechanism for effecting intermittent reciprocatory movements of the drill holder to retract the drill holder from and return it to an operative drilling position, clutch-means adapted to drive the crank mechanism, a lever for controlling -the clutch means, a plurality of stationary means provided upon the machine and Vspaced in the direction of feed, a, spring-loaded actuating pawl mounted on the lever for intermittently co-operating With one of said stationary means, and further means operable by said crank mechanism 8 forivaryiig the operativeiposition of the drill holder to nullify the feed increment imparted to the tool slide during each reciprocation.

HORACE RAY ADCOCKn References Cited in the ille of this patent UNITED STATES PATENTS 10 Number Name Date 599,356 Reece Feb. 26, 1898 1,748,476 Hanson i Feb. 25, 1930 2,460,156 Vanderhide Jan. Z5, 1949 

